
Workflow Developer & Tester
Webbing • Belgrade, Central Serbia, Serbia
**Role & seniority: ** Backend Developer (Go/Java) — hands-on implementation; supports Sr. Developer; expected pair programming.
**Stack/tools: **
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Go (primary); Java acceptable with strong fundamentals
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Temporal workflow (Go activities)
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REST APIs
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PostgreSQL (schema, indexes, query plans)
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Testing: unit + integration + end-to-end; mocks for NEs
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CI/CD test automation
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Event-driven: RabbitMQ / Kafka / Redis Pub-Sub
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Kubernetes (basic)
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Docker (nice to have)
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Perf/load testing: k6 / Locust / JMeter (advantage)
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Top 3 responsibilities:
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Implement Temporal workflow activities and integrations (HSS adapter, PCRF adapter, inventory update) with unit tests from day one.
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Design/build Inventory Management DB (tables/indexes/partitioning for ~30M records) and implement bulk import tooling + MNP hooks.
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Develop Inventory REST APIs (allocate/reserve/release/query) and deliver integration/e2e test coverage plus load/stress validation.
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Must-have skills:
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2–4 years backend production experience
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Strong Go (or willing to transition from Java to Go)
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REST API development with automated test suites
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PostgreSQL proficiency (queries, indexes, query plans)
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Strong unit + integration testing ownership
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Git collaboration (PRs, reviews)
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Event-driven architecture experience (RabbitMQ/Kafka/Redis Pub-Sub)
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Basic Kubernetes
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Full Description
Implement Temporal workflow activities in Go: HSS adapter, PCRF adapter, Inventory update. Build and validate unit tests for all workflow activities from day one.
Build the Inventory Management Database: tables, indexes, partitioning for 30M records.
Build bulk import tooling: CSV → ICCID/IMSI/MSISDN range ingestion from vendor. Implement REST API endpoints for Inventory DB (allocate, reserve, release, query SIM records).
Write integration tests: workflow → mock NE → database assertions. Support Sr. Developer on all workflow development tasks — pair programming expected.
End-to-end test suite: full provisioning flow from SIM activation to order closed.
Load and stress testing: simulate peak TPS provisioning against all systems.
Test automation: CI pipeline integration for all workflow and API tests.
HSS sync integration: IMSI allocation state reflected in HSS (mock → real NE). MNP (number portability) hooks in Inventory DB.
UAT support: reproduce bugs, write regression tests, validate fixes.
Requirements Must Have 2–4 years backend software development in production environments. Go or Java — primary development language for this role is Go. Java accepted if strong fundamentals and willing to work in Go (we will support the transition). REST API development — building APIs consumed by other services and tested by automated suites. PostgreSQL — table design, indexes, writing queries, understanding query plans . Unit and integration testing — writing tests is a first-class responsibility, not an afterthought. Git — branching, pull requests, code review participation. Experience with event-driven architectures using RabbitMQ, Kafka, or Redis Pub/Sub. Basic Kubernetes knowledge — understanding how your workloads are deployed. Ability to work under technical direction of a senior lead and execute quickly. Fluent English. Strong Advantage
*** Any workflow engine experience:** Temporal, Camunda, Apache Airflow, AWS Step Functions.
- Telecom or BSS/OSS background — understanding of SIM lifecycle, provisioning, activation.
*** Test framework experience:** Go testing, Testify, mock frameworks.
*** Load testing tools:** k6, Locust, JMeter — running and interpreting results.
- Docker — building and running containerised services.
- Experience with event-sourced or append-only database patterns. Nice to Have Temporal.io SDK experience — even personal/side project counts. Python — useful for scripting, test tooling, data processing. Prometheus — understanding how to instrument code with metrics.
Telecom protocol familiarity: Diameter, SS7, SMPP.
About Webbing Founded in early 2010, Webbing is a global data MVNO that delivers enterprise grade, global connectivity and IoT services across more than 200 countries and 600+ mobile carriers' networks. Webbing's secured network delivers network protection and web content intelligence. Enterprise customers can manage, monitor, and optimize data usage in real-time with Webbing's powerful software platform. Gain visibility by application type and have the power to white list applications and limit non-business applications with the click of a button, saving money and improving compliance.
What we offer Fully remote An exciting and challenging greenfield platform with great skill and knowledge development opportunities. The opportunity to join a team of highly professional specialists in an international environment. The opportunity for professional development within a reputable international innovative and growing company.